TY - JOUR
T1 - Structure and morphology of self-assembled 3-mercaptopropyltrimethoxysilane layers on silicon oxide
AU - Hu, Minghui
AU - Noda, Suguru
AU - Okubo, Tatsuya
AU - Yamaguchi, Yukio
AU - Komiyama, Hiroshi
N1 - Funding Information:
This work was supported by the “Research for the Future” Program of the Japan Society for the Promotion of Science (JSPS-RFTF 96P00402). We thank Prof. Shinichi Nakao and Mr. Shinya Maenosono for assisting with the contact angle and AFM measurements, and we thank Mr. Toshio Ohsawa, Ms. Yoshiko Tsuji, and Dr. Seiichi Takami (Department of Biochemistry and Engineering, Tohoku University) for helpful discussions and comments.
Copyright:
Copyright 2019 Elsevier B.V., All rights reserved.
PY - 2001/9/21
Y1 - 2001/9/21
N2 - Self-assembled 3-mercaptopropyltrimethoxysilane (MPTMS, (CH 3 O) 3 SiCH 2 CH 2 CH 2 SH) layers on hydroxyl-terminated silicon oxide (SiO 2 ) were prepared at MPTMS concentrations ranging from 5 × 10 -3 to 4 × 10 -2 M. The surface structure and morphology of MPTMS layers were characterized by X-ray photoelectron spectroscopy (XPS), contact angle measurements, scanning electron microscopy (SEM), and atomic force microscopy (AFM). We found that the MPTMS layers on SiO 2 consisted of dispersed domains 20-200nm in diameter, instead of continuous, flat monolayers. With increasing MPTMS concentration, the domain shape changed from flat to steep. Flat domains were composed of well-ordered monolayers with thiol headgroups uniformly distributed on the uppermost surface, whereas steep domains were composed of disordered polymers with randomly distributed thiol headgroups on the uppermost surface. These results indicate that MPTMS molecules show good self-assembly at an MPTMS concentration of 5 × 10 -3 M, but not above this concentration. The effect of MPTMS concentration on the structure and morphology of MPTMS layers might be due to the competition between self-polymerization and surface dehydration reactions, which depends on the trace quantity of water in the solvent and on the SiO 2 surface. Our research further indicates that MPTMS and water concentrations are the controlling parameters for preparing well-ordered, self-assembled MPTMS monolayers on SiO 2 .
AB - Self-assembled 3-mercaptopropyltrimethoxysilane (MPTMS, (CH 3 O) 3 SiCH 2 CH 2 CH 2 SH) layers on hydroxyl-terminated silicon oxide (SiO 2 ) were prepared at MPTMS concentrations ranging from 5 × 10 -3 to 4 × 10 -2 M. The surface structure and morphology of MPTMS layers were characterized by X-ray photoelectron spectroscopy (XPS), contact angle measurements, scanning electron microscopy (SEM), and atomic force microscopy (AFM). We found that the MPTMS layers on SiO 2 consisted of dispersed domains 20-200nm in diameter, instead of continuous, flat monolayers. With increasing MPTMS concentration, the domain shape changed from flat to steep. Flat domains were composed of well-ordered monolayers with thiol headgroups uniformly distributed on the uppermost surface, whereas steep domains were composed of disordered polymers with randomly distributed thiol headgroups on the uppermost surface. These results indicate that MPTMS molecules show good self-assembly at an MPTMS concentration of 5 × 10 -3 M, but not above this concentration. The effect of MPTMS concentration on the structure and morphology of MPTMS layers might be due to the competition between self-polymerization and surface dehydration reactions, which depends on the trace quantity of water in the solvent and on the SiO 2 surface. Our research further indicates that MPTMS and water concentrations are the controlling parameters for preparing well-ordered, self-assembled MPTMS monolayers on SiO 2 .
KW - Atomic force microscopy
KW - Self-assembled monolayers
KW - Silicon oxide
KW - Surface modification
KW - X-ray photoelectron spectroscopy
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U2 - 10.1016/S0169-4332(01)00399-3
DO - 10.1016/S0169-4332(01)00399-3
M3 - Article
AN - SCOPUS:0035928972
SN - 0169-4332
VL - 181
SP - 307
EP - 316
JO - Applied Surface Science
JF - Applied Surface Science
IS - 3-4
ER -